So.... I BLEW up my motor.... literally...

#6

So it DID indeed spit a shim. #3 intake valve shim is gone. Cams are fried (luckily I still have my stock ones).
Other than that I think everything is still ok.
So what now? Besides cams, valve cover gasket and valve cover of course. New buckets and shims? How do I ensure this never happens again?
Should I take the whole head off or is it safe to assume the rest of the motor is fine?

Myself, I would pull the head, just to be safe. Check your valve ,valve spring, retainer and bucket. If there is no other damage, to the head? Replace the damaged parts.

Larry would know if web cams are repairable or not? Even with stock cams, rebuild the damage and keep the valves adjusted.

Life will get better, don't shit-can the bike. Now that you have gone this far, learn and move on from this deal.

It is called EXPERIENCE! Experience is the best teacher, but the price is high.

No worries my friend, your damage doesn't look that bad, from the pictures. I saw one spit a shim at 10,000+ rpm's. The shim came out just above the 1 & 2 exhaust ports. It looked like a large bullet hole, in the head.

Put on your happy face and get busy!

. Hello my friend Hello Looks like you lucked out. You worried something fell down in the bottom of motor ?Pull the pan ..Neil Diamond Rules

Brendan,

Something ate that lobe away and that's why it spit the shim.

You have grit through the motor now from that lobe. It's got to come out.

Does the bucket spin in the bore?

Is the top end getting oil?

Larry C

I'm wondering what was rubbing on the spots pointed to by the yellow arrows in this photo.

Better photo

Here's the better pic

How much of the shim have you found?

I haven't found any of the shim yet. Only went as far as pulling the valve cover.

larrycavan wrote:

Here's the better pic

How much of the shim have you found?

looks like the bucket ate the lobe after the shim cam out. Seen this on my own bike from roting the motor forgetting i had no shim in one bucket. Ir maybe I started it can't remember. That cam lobe looks pointy on the tip. That right there seems to be part of the whole deal. My cams are .407 but they don't look like that. Some of the geometry is rather BOOOM!:woohoo:

Man that sucks but it is fixable......Looks like its gonna be a "Hot August Night"..... Wait ain't that a Neil Diamond song.......... Sorry I couldn't resist

Am thinking the original Z1 valve shims had a center dimple which was blamed for shim fracture, which design was replaced early on with a non-dimpled version. Hopefully, an obsolete dimpled shim wasn't the culprit here.

While unlikely in this case, other reasons for shim failure might include weakening from "regrinding" attempts toward reducing shim thickness (which remove the shim's hardened surface treatment), or using shim-stock under the shim, or using the "wrong" shim intended for a different engine.

Good Luck!